Phase control system



Sept. 19, 1950 G, E, U Dy 2,523,161

PHASE CONTROL SYSTEM Filed Sept. 15, 1946 74/ @5411 V W mm IN VEN TOR.

M,% VAN.

Patented Sept. 19, 1950 PHASE CONTROL SYSTEM Gustav E. Undy, Detroit, Mich., assignor to Weltronic Company, Detroit, Mich., a corporation of Michigan Application September 13, 1946, Serial N 0. 696,945

2 Claims.

This invention relates generally to electrical control systems and more particularly to an adjustable phase-shifting system. Objects of this invention are to provide a simplified phase-shifting system of the character described; to provide a system in which the phase of the output of voltage with respect to that of the input of voltage may be adjusted by a single control element; to provide such a system in which the single control element is a common potentiometer resistor; to provide in such a single-control phase-shifting system means whereby the limit of phase shift of the output voltage with respect to the input voltage may be selectively adjusted, and to generally improve phase-shifting systems of the character described.

With the above, as well as other more detailed objects in view which will appear from the following description and the appended claims, there is shown in the drawing a preferred but illustrative embodiment of the invention.

In the drawing which is to be taken as a part of this specification there is illustrated diagrammatically a control system embodying the invention.

A phase-shifting control system designated I comprises a transformer TI a dephasing element or condenser CI, a phase-adjusting element or a potentiometer RI and a pair of adjustable phaseshift angle-limiting resistors R2 and R3. The transformer TI has a single iron core 2, a pair of secondary windings 4 and 6, and a center tapped winding providing a pair of primary input windings 8 and I0. The common terminal of the windings 8 and I is connected by means of a conductor I2 to one line switch LSI of a suitable source of alternating current supply. The free terminals of the primary windings 8 and I0 are connected respectively to variable resistors R2 and R3. The opposite terminal of the resistor R2 is connected through the condenser CI to one end terminal of the potentiometer resistor RI. The other end terminal of the potentiometer resistor RI is connected to the terminal of the variable resistor R3 opposite that to which the winding I 0 is connected. A conductor l4 connects the adjustable control or wiper element I5 of the potentiometer resistor RI to the other line switch LS2 of the alternating current source. If de sired, a resistor R4 may be connected in shunt with the end terminals of the resistor RI for stabilizing purposes.

It is thought that the remaining details of the system may best be understood with reference to a description of the operation thereof.

Assuming that the line switches LSI and LS2 are in closed circuit position an alternating current potential will be supplied to the system I by the conductors I2 and across the capacitive circuit I6 comprising the winding 8, resistor R2, condenser CI and lefthand portion of the potentiometer resistor RI and the other or inductive circuit I8 comprising the winding III, the resistor R3 and the righthand portion of the potentiometer resistor RI.

The value of the capacitor CI is so chosen with respect to the impedance of the winding 8 that the current through the capacitive circuit I 6 will lead the voltage by an angle dependent upon the relative resistive and capacitive reactance of this circuit. The current through the inductive circuit I8 will lag the voltage by an angle determined by the relative proportion of the resistive and inductive reactance of this circuit. The currents flowing through the windings 8 and Ill, therefore, will have an angle therebetween which is equal to the sum of the angles of lead and lag of the current in the two circuits I6 and I8. Since the windings 8 and I0 are wound in opposite directions with respect to each other when they are considered in their present parallelly connected relation, When the current in winding 8 is leading the current in the winding III by exactly 180 the two currents will be additive in producing a flux in the core 2 and the voltage output of the windings 4 and 6 will be out of phase with the voltage across the conductors I2 and I4.

If the adjustable arm of the potentiometer resistor RI is adjusted so that substantially all of the resistance of the resistor RI is placed in the circuit I8, substantially no current will flow through the winding I0 and the flux induced in the core 2 of the transformer TI will be substantially that due to the winding 8 by a current flowing therethrough which leads the voltage of the conductors I2 and I 4. If the resistor R2 is set for zero resistance, the output voltage of the secondary windings 4 and 6 of the transformer TI, assuming them to be properly polarized, will be substantially in phase with the voltage of the conductors I2 and I4. If now the resistor R2 is adjusted upwardly in value, the voltage induced in the secondary windings 4 and 6 will become lagging by an angle proportional to the relative value of the resistance and capacitance of the circuit.

If the movable arm of the potentiometer resistor RI is adjusted so that all of its resistance is in series circuit with the circuit I6, substantially the entire flux induced in the core 2 of the transformer TI is due to the current flowing through the primary winding I 0 which because I4 placing a potential angle of lag of the voltage will be decreased in proportion to the ratio of resistance to inductance in this circuit.

If the movable arm of the potentiometer resistor RI is set at an intermediate point, current will flow through both of the primary windings 8 and 10 of the transformer Tl which willcause flux to be induced in the core 2 of the transformer Tl which is proportionalto the vector difierence of thecurrents in the windings B-and l0.- Therefore, at intermediate adjustable points of the potentiometer resistor RI the voltages induced in the secondary windings l and 6 will be somewhere between an in-phase condition and an 180 lagging condition with respect to the voltage of the conductors l2 and 14 depending upon whether the circuit is predominantly inductive or capacitive in nature.

It may now be seen that the system of the invention utilizes a minimum number of control elements and is simple in manufacture and operation. A single, simple control element, such as a potentiometer resistor, is used to shift an output voltage of the system between predetermined limits, these limits being predetermined by adjustable resistors.

What is claimed and is desired to be secured by United States Letters Patent is as follows? 1, The combination of alternating current supply terminals, a transformer having a primary winding and a plurality of secondary windings, each of said windings having a pair of terminals, said primary winding having a terminal intermediate its said pair of terminals, a.

pair of elements connected in series between said pair of primary terminals, one of said elements being reactive for producing a dephased current in said primary winding, means for adjusting the magnitude of said dephased current and positioned in series circuit with and intermediate said elements, and circuit means connecting one of said supply terminals to said intermediate terminal and the other of said supply terminals to said adjusting means, each said pair of secondary terminals being adapted to be connected to separate means wherein isolated voltages phased as desired with respect to that of said supply terminals is provided.

2. The combination of alternating current 1 supply terminals, a transformer having a primary winding and a secondary winding, each of said windings having a pair of terminals, said primary winding having a terminal intermediate itssaid pair of terminals, a pair of elements connected in series between said pair of primary terminals, one of said elements being reactive for-producing a dephased current in said primary winding, means for adjusting the magnitude of said dephased current and positioned in series circuit with and intermediate said elements, and circuit means connecting one of said supply terminals to said intermediate terminal and the other of said supply terminals to said adjusting means, said pair of secondary terminals being adapted to be connected to means wherein a voltage phased as desired with respect to that of said supply terminals is provided.

GUSTAV E. UNDY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,030,202 Godsey Feb. 11, 1936 2,229,449 Garman Jan. 21, 1941 2,393,884 Callender Jan. 29, 1946 2,411,423 Guptill, Nov. 19, 1946 

